The CV4501 pentode specification was issued by the Ministry of Aviation and so this was probably designed for airborne equipment. The frequency of operation has not yet been determined. The commercial data-sheet has not yet been found.
The base is a B8D/F to denote the flying leads.
The gaps in the bright anode allow the wire grids to be viewed. All three can be seen.
A closer look at the grids.
The thin glass tube envelope is 9 mm in diameter, and excluding the base wires is 37 mm tall.
Reference: Datasheet. Type CV4501 was first introduced in 1960.